Boeing starts 787 horizontal stabiliser inspections

Boeing has begun horizontal stabiliser inspections on two of its 787 flight test aircraft after it disclosed workmanship errors by supplier Alenia Aeronautica that could reduce the fatigue life of the parts.

ZA002 and ZA003, both Rolls-Royce powered 787 flight test aircraft will be inspected today at Boeing Field in Seattle and Pinal Airpark in Marana, Arizona, respectively. Neither aircraft will return to flight operations until the one to two-day inspections are complete, says Boeing.

Twenty-three of twenty-five horizontal stabilisers already shipped from Italy are installed on 787s, five of which are flying on flight test aircraft. ZA001, ZA004 and ZA005 are all currently in maintenance and instrumentation installation layup.

Scott Fancher, 787 programme vice president and general manager, declined to say which aircraft or how many have the horizontal stabiliser workmanship issues, saying only that he anticipates the rework to take eight days.

Additionally, an internal investigation has been launched as to how the workmanship issues escaped Boeing's notice during 25 shipsets delivered over three years from Alenia.

"It turns out [the issue] is fairly deeply imbedded in the assembly, so we're in the process of auditing the records associated with that to understand whether or not there's a systemic issue with the escape or whether it's a one off," says Fancher.

The rework focuses on two shims, or engineered gap fillers, in the aft part of the horizontal stabiliser and requires the re-torquing of 12 fasteners on either side of the structure, says Fancher.

Programme sources say the shims used to fill gaps in the horizontal stabiliser became compressed after fasteners were over-torqued as a means of pulling the surfaces together, introducing a "pre-load" condition reducing the long-term fatigue life of the structure.

Fancher concedes it is possible that some flight test operations will need to be re-sequenced due to the inspections or potential rework, but adds, "We think that's entirely manageable given our schedules and our status."

Fancher also adds that while the inspection or rework is being undertaken, ground testing can proceed.

Boeing anticipates 2,400h of flight testing and 3,100h of ground testing on its Rolls-Royce Trent 1000 powered test fleet to achieve certification and delivery to Japan's All Nippon Airways by year-end. To date, Boeing has accomplished nearly 1,060h of flying on its Trent 1000 fleet.